Action Points

Note that this surveillance data from the CDC suggests that roughly 10% of Zika-infected babies in the US have a Zika-associated abnormality.

The data also suggests that the majority of children of Zika-infected mothers do not receive neuroimaging.

About one in 10 pregnant women with confirmed laboratory evidence of Zika infection had a fetus or baby with Zika-associated birth defects, according to CDC researchers.

In a subset of 250 completed pregnancies from the U.S. Zika Pregnancy Registry, about 24 (10%, 95% CI 7%-14%) had birth defects related to congenital Zika virus infection, such as microcephaly, brain abnormalities, or developmental difficulties, reported Megan R. Reynolds, MPH, of the CDC in Atlanta, and colleagues.

This number was higher (around 15%) for pregnancies with confirmed Zika virus infection in the first trimester, they wrote in "Vital Signs" of the Morbidity and Mortality Weekly Report.

However, only 221 of the 895 live-born infants whose mothers had evidence of Zika infection (25%) received any neuroimaging from a head ultrasound or CT scan at birth, according to Reynolds' group. Imaging could help detect brain abnormalities not visible at birth, and the CDC currently recommends neuroimaging for any infant whose mother has Zika.

"The shocking finding is that, despite much outreach by health officials, the majority of infants with possible Zika infection do not receive brain imaging," wrote Amesh Adalja, MD, of Johns Hopkins Center for Health Security in Baltimore, in an email to MedPage Today. He was not involved in the CDC report.

"Such a gap attests to the difficulty in disseminating clinical information to frontline clinicians -- something that hampers responses to infectious disease emergencies like Zika," said Adalja, a spokesperson for the Infectious Diseases Society of America.

In a press call, CDC acting director Anne Schuchat, MD, said that the U.S. Zika Pregnancy Registry showed pregnancies with evidence of Zika infection in 44 states. She added that 30 to 40 new cases of Zika among pregnant women are reported every week in the U.S.

Schuchat characterized "the majority" of these cases as being related to travel to Zika-infected areas, but said that because CDC does not release state-by-state data to protect the privacy of pregnant women, there was no way to know if any cases were locally acquired from a specific state, like Florida.

The report examined nearly 1,300 women with evidence of Zika infection, as reported to the U.S. Zika Pregnancy Registry from Jan. 15 to Dec. 27, 2016. Of the 972 completed pregnancies in 2016, 51 (5%) had evidence of Zika-associated birth defects (45 live births and six pregnancy losses).

Because of the limited imaging testing, the researchers said it is possible that the current data may underestimate the impact of Zika.

Schuchat said that she hoped this report would help raise awareness among clinicians to do this type of imaging among babies at risk for Zika. She added that it is "relatively new" and many clinicians may not be aware of it yet or their reasons for not doing it may be "complex."

"Clinicians anywhere in the country need to be aware how to screen for Zika exposure, diagnose it in their patients, and monitor for follow-up," Schuchat said.

In addition, while 585 of these 895 infants (65%) were tested for Zika at birth, this leaves about a third who received no Zika testing when they were born.

Prior to the Zika epidemic, baseline prevalence for birth defects, such as those seen with Zika virus, was about three in 1,000, said Schuchat. It is now more than 30 times higher than the baseline prevalence.

Schuchat emphasized that the Zika outbreak "is not going away," so raising awareness about prevention is more important than ever.

"Healthcare providers play a key role in prevention efforts for Zika," she said. "They should encourage pregnant women to follow CDC recommendations, ask about Zika exposure, and provide testing and follow-up care to babies, to monitor baby's development."

Schuchat said the cost of treating an infant with microcephaly is nearly $4 million, and nearly $10 million if the child survives into adulthood.

Reynolds and co-authors disclosed no relevant relationships with industry.